The present invention relates generally to a hermetic compressor and, more particularly, to a compressor having a reciprocating piston including a suction valve assembly and a discharge valve assembly.
The general prior art of hermetic compressors comprise a hermetically sealed housing having a compressor mechanism mounted therein. The compressor mechanism may include a crankcase or a cylinder block defining a compression chamber therein in which gaseous refrigerant is compressed and subsequently discharged.
A disadvantage to prior compressor designs is that there is always a certain volume left in the cylinder when the piston is at top dead center position. This volume of gas never leaves the cylinder but is repetitively compressed and re-expanded during the reciprocation of the piston. Re-expansion volume causes a major loss of energy in a compressor.
Another disadvantage of prior compressor valve designs is that at high compression ratios, the discharge valves are noisy and do not close fast enough for efficient operation. Small discharge valve ports in these compressors require a large discharge valve lift for operation. The larger the amount of valve lift the slower the valve closure, since the valve has to travel a longer distance to close. Slow closing valves permit leakage back into the compression space during operation thereby lowering the compressor's efficiency.
Small discharge ports also create a large pressure drop in the compressed fluid as it travels through the ports. This pressure drop lowers the volumetric efficiency of the compressor.